WASHINGTON -- Taking your blood pressure at home might give more accurate results than having your blood pressure taken in a doctor's office, according to a new study. But some physicians say it really depends on the monitor you are using.

HIGH BLOOD PRESSURE Slideshow: High-Sodium Surprises In Depth: Blood Pressure Guide Survey: Have High Blood Pressure? Interactive: Virtual Heart Calculator: Heart Risk Test

Thomasine Williams has high blood pressure. And she needs to watch it carefully, because if her blood pressure gets too high, it could lead to a heart attack or a stroke. At first, she tried to monitor her pressure with three different home devices. They didn't work.

"I found with the wrist monitor, you could take it, and then five minutes later, you could take it again and it was entirely different -- drastically different," said Williams. "I would take my pressure at home and it would be low, and then I would come in here and then it would be high, and it was just never on track."

Dr. Patricia Davidson, a cardiologist at George Washington University Hospital in Washington, D.C., encourages patients to use home blood pressure monitors, but she said the quality and results can really vary with these devices.

"I insist that the patient bring their monitors in several times a year so that I can check it against the blood pressure mercury that is still considered the 'gold standard,'" she said.

A study published in Wednesday's issue of the Journal of the American Medical Association found that these home monitors produce accurate blood pressure readings and predict cardiac problems as well as, if not better than, office monitors.

French researchers analyzed blood pressure readings from nearly 5,000 elderly patients. They found that a number of factors, including the "white coat syndrome" -- the anxiety of seeing a doctor, can have some effect on readings.

But Davidson said measuring your blood pressure at home isn't always ideal.

"You don't want to only take your blood pressure when you are home relaxing with your feet up watching your favorite TV show, because your goal is not to find your lowest blood pressure; your goal is to find your highest blood pressure," she said.

Davidson recommends staying away from the blood pressure monitors at the drugstore or grocery store because they may not be checked regularly. You should talk to your doctor before you buy your own monitor.

Check the quality of your purchase; some of them are tested by consumer groups and magazines. And check your machine with your doctor every few months to make sure the readings are accurate.

It's better to invest in one high-quality blood pressure monitor instead of several less expensive models that may not work as well.

Thomasine Williams knows the consequences: "They're in a drawer somewhere. I don't even bother."

Study Abstract